ONCE, Lina Killick was standing all alone in the long, cold corridor of an old mansion when she felt something wrap itself around her belly and whisper "Help me" into her ear.

She couldn't see what was grabbing her, but she could feel a skirt swishing spookily around the back of her ankles.

"I was later told that the Gloucestershire mansion we were in was haunted by a maid who had had an affair with the master of the house and fallen pregnant in the mid 1800s," said Lina.

"She had jumped out of the window and killed herself rather than deal with the shame of having a fatherless child."

Lina and her husband, Charlie, are founder members of Two Worlds Paranormal Investigation, and regularly visit old buildings to check them out for paranormal activity.

They sometimes choose places they would like to visit, or are invited there by the buildings' owners who want to find out whether their premises are haunted – and they have seen and heard enough to shake even the most hardened ghost non-believer.

"We have had some very intense experiences," said Lina (30). "And we have been scared. We were in a house in Essex once which had a series of underground tunnels.

"I was standing in a tunnel during an investigation, and suddenly the worst agony I have ever experienced flashed through the whole of my left side, from the stomach down, just for a second. It was horrific.

"We then heard footsteps, and then the air filled with the smell of gunpowder, it was very strong, unmistakable. Some of the members of the team began to freak out and left, and I have to admit, it was very frightening indeed."

The couple found out that the house had been built on the site of an old Second World War fort, and the tunnels had been used to store bombs and ammunition.

There had been an accident there one night, and a man had been blown up, losing his leg and taking blows in the stomach and hip.

"Most people think we're mad when we tell them about Two Worlds, but then they add 'Well now you mention it,' and have a story of their own to tell about a ghost," said Lina, who works in IT.

"We like meeting sceptical people because they tend to be rational and logical, and can help us to try to understand what we have experienced, and that's what we want to do. We would love to know the truth behind paranormal activity, we would love a scientific explanation.

"The worst people to deal with are the people that believe too much. Some people will see dust on their floor and take it as evidence that their house is haunted, and then get disappointed when we don't find anything."

Lina's fascination with the supernatural began when she was four, and her sister was born. Her granny gave her a crystal ball which she used to play with. "Nothing came of it," she said.